Method of dehydrating a crop

ABSTRACT

This method of dehydrating a crop such as alfalfa or the like includes the step of spraying a coating of water on the crop just prior to advancement of the crop into the heated dehydrator drum.

United States Patent lnventor Stanley P. Thompson Box 7, St. Marys,Kans. 66536 847,270

Aug. 4, 1969 July 20, 1971 Appl. No. Filed Patented METHOD OFDEHYDRATING A CROP 8 Claims, 3 Drawing Figs.

US. Cl 34/9, 34/12 Int. Cl F26b 3/00 Field of Search 34/9, 12; 263/32[56] References Cited UNITED STATES PATENTS 2,227,634 1/1941 Dalin 34/9X 2,472,794 6/1949 Cothran 34/9 X 2,900,737 8/1959 Heller 34/123,396,476 8/1968 Eaves 263/32 X Primary Examiner-John J. CambyAtt0meyD0n M. Bradley ABSTRACT: This method of dehydrating a crop suchas alfalfa or the like includes the step of spraying a coating of wateron the crop just prior to advancement of the crop into the heateddehydrator drum.

PATENlfinJuLzoasn 3,593 429 F; 1 INVENTOR STANLEY I? THOMPSON BY MW? 5MATTORNEY METHOD or-nsnvnnx'rmo A CROP v This invention relates to thetreatment of feed products, and

gaseslvaporize the moisture contained .in the crop to produce a.

dried-product which'may. beground andpelletedand whichlis suitable, forexample, forv use as animal feed.

Thetemperaturesto which the-crop 'is exposed in the drum.

are'substantially high. The crop'is-usuallyretained inthe drum untilsufiicient evaporation ofthe moisture in the crop permits conveyance ofthedriedproduct bypneumatic or other means from the outlet end of thedrum. The relativelylhigh temperatures. to which the crop is subjected.do not, however, uniformly affect the various portions of the crop. Forexample, the leaves of :crops such as alfalfa are dried by the hotproducts of combustion much more rapidly than are themore coarse stemsof the alfalfa .plant. The moisture in the stems is'brought to thetemperature for rapid evaporation only after dwelling in theheatedenvironment a substantial period of time compared to thetimenecessary for. drying theleaves.

Although the leaves and relatively small particles are usually conveyedthrough the drum at a faster rate, they still become charred or burnedas a result of the time-temperature relationship encountered in thedrum. This overheating or burning, of the crop .results in production ofobjectionable smoke which emanates from. the dehydration plant. It alsodestroys much of the beneficial feed value of the crop, to say nothing.of the objectionable taste imparted to. the cropdiminishing thepalatability ofthelfinal product.

Relatively'fine fibers or hairs on both the leaves and stems are quicklyburned when the crop enters the dehydrator. Further, it is believedthatbeneficialcr'op constitutients such asxanthophyll and whichcontributevitamin E and thelike are damaged or destroyed by theelevation of the crop components to thepoint where burning orcharringof. the com ponents-begins. It is believed that a mold or thelike on the surface of the crop may contribute to the presence ofxanthophyll. This mold on the surface is' quickly destroyed when thecrop is dehydrated by conventional methods.

Accordingly, it is a primary object'of'thisinvention to provide a methodfor preventing the. destruction by heat of the relatively vulnerablecrop components while the relatively coarsecomponentsare heated to therequisite temperature for evaporating the moisture therefrom. 1

ln carryingout the foregoing object, it is an important object of thepresent invention to coat substantially the entire outer surface of thecrop before introducing the latter to the heated dehydration gases sothat the evaporation of the moisture from the outer surface-protects theunderlying crop surface portions-from the bumingelfects-ofv the heatuntil the components are moved to relatively cooler regions in thedehydrator drum.

Another object of this invention. is the protection of highlyheat'destructible components of the crop to prevent the loss of valuablenutrients and vitamins and other beneficial vconstituents of the cropwhile the same is subjected to the action of dehydration gases.

Anotherobject of the invention is to provide a dehydration methodwherein the gases emanating from the dehydrator are relatively free oreven entirely free of smoke from charred or bumedcrop particles.

Still a further object of the invention is to provide a dehydratingprocess wherein relatively large quantities of steam are-produced withinthe dehydrating drumwhich steam v tends to transfer heat throughoutthedrum to'enhance the overall efficiency of the dehydrating operation.

A yet further object of this invention is to provide a process whereinthe benefits'of using a cone-typefurnace are obtained without anyharmful effects occurring as a result of the relatively hightemperatures at the inlet end of the dehydrator drum .which areproduced'by furnaces of this type.

These and other important objects of this invention will be furtherexplained or will become apparent from the following I invention;

FIG. 2 is a bottom plan view of a sprayer-head which may be utilized incarrying out this invention; and

FIG. 3is a detailed, vertical, cross-sectional view through a spraybarused in carrying out the method of this invention.

Apparatus for carrying outthe method'of this invention is broadlydesignated by the reference numeral 10in the drawing and includes anelongated axially rotatable dehydration drum 12 which is in fluidcommunication at one end thereof with a cone-shaped furnace 14 providedwith blower means 16 for directing air for sustaining combustion intothe furnace 14. Material such as a crop in the nature of alfalfa or thelike is fed to drum l2from an unloading ramp broadly designated 18,through a slat-type conveyor 20' and a transversely extending augerconveyor 22. The latter communicates with the inlet end of drum 12adjacent the discharge end of furnace 14 so that the crop emanatingfromconveyor 22 is subjected to the relatively hot gases produced bycombustion in furnace 14.

A fan 24 may be placed in communication with the outlet end of drum 12for pulling the hot products of combustion and the dehydrated cropmaterial from drum 12. Manifestly, fan 24 is operated by motor' 26 at arate of speed calculated to remove the crop products from the dehydratordrum after the same have become sufficiently light through evaporationof the moisture content the'refromin the drum to permit entrainment inthe fluid stream;

The dehydrated crop material may be conveyed pneumatically througha'tube 28 to a cyclone-typeseparator 30. Here, in separator 30, the cropproducts are separated from the fluid stream whereupon'the products maybe pelletized or otherwise treated for rendering the products usable asan animal feed or the like. It will be understood, of course, that thedehydrated products could be subjected to the operation of ahammermillor the like following dehydration. Further, it should beunderstood that apparatus for crushing stems or like material could beinterposed in apparatus 10 upstream from the inlet end of drum 12 torender the crop material more easily dehydrated when the material isplaced in the hot gaseous environment within drum 12. The apparatusheretofore described is entirely conventional and, by itself, forms nopart of the instant invention. According to the method of dehydratingpursuant to this invention, however, water is applied to the outersurface of the crop material prior'to the passage of the material intothe dehydrator drum. Any suitable apparatus may be employed for thispurpose. The apparatus illustrated in the drawings for this purpose isbroadly designated by the reference numeral 32 and includes an elongatedtubular spray bar 34. Bar 34 extends across conveyor 18 and is providedwith a plurality of downwardly directed nozzle heads 36 communicatingwith bar 34 through fittings 38 disposed at spaced intervals alongbar'34 as shown in the drawing. Bar 34 is in fluid communication with asource of water (not shown) through pipe 40.

Manifestly, apparatus 32 could be disposed at any point upstream fromthe inlet end of drum [2. If stem-crushing apparatus (not shown) is tobe utilized for breaking down the fibrous structure of the crop prior todehydration of the latter, the station at which water is applied to thecrop is preferably located downstream from such stem-crushing apparatus.

As the crop is advanced towards the inlet of the dehydrator drum, wateris applied to the crop at a rate and in sufficient amounts forthoroughly coating the outer surface of the leaves and stems of thecrop. It has been found empirically that beneficial results are to beobtained if water is applied to the crop in amounts ranging from poundsof water per ton of dry material to approximately 1,500 pounds of waterper ton of dry material. Apparently, amounts in excess of 1,500 poundsof water per ton of dry material do not produce beneficial resultsgreater than that which may be achieved in applying water atapproximately the l,500 pound rate.

Following application of water to the crop for wetting the outer surfacethereof, the crop is introduced into the heated gas environment in druml2. Normally, the temperatures encountered by the crop in the drum rangefrom approximately 2,500 F. to approximately 3,400 F. The temperaturesat the outlet end of the drum range from approximately 200 F. toapproximately 230 F. This presupposes a length of approxi mately 36 feetfor drum 12 and the use ofa cone-type burner as illustrated in FlG. l.

The water on the outer surface of the components of the crop preventsthe relatively easily destroyed constituents from burning Actually, thecooling effect caused by the evapora tion of the water from the surfaceof these easily destroyed constituents serves to protect the latter.This protection remains for a sufficient period of time to permittransfer of the material longitudinally of the drum toward the outletend thereof. The evaporation of this protective water is not completeduntil the more vulnerable constituents of the crop have escaped therelatively high temperatures at the inlet end of the drum and havereached the cooler regions near the outlet.

The relatively light portions such as leaves and particulate material donot remain in the drum nearly as long as the relatively coarse stems.Further, the rate of transfer of the coarse material through the drum issomewhat slower. Accordingly, the relatively coarse materials aresubjected to the high temperatures for a sufficient period of time tonot only evaporate the water but to insure evaporation of the moisturefrom within the stems.

It is believed that the steam produced in the dehydrator drum as aresult of the water coating for the crop aids in the transfer of heatlongitudinally through the dehydrator drum. This produces a environmentof heated gases which is more uniform throughout the length of the drumand this also helps to eliminate burning or charring of the surface andvulnerable portions of the crop during dehydration.

It is desirable that as much of the outer surface of each plantcomprising the crop be coated with water as is possible. To this end, ithas been found desirable to introduce quantities of a suitable wettingagent such as a detergent or the like into the water prior to applyingthe water to the crop. Obviously, the amount of agent required for anyparticular dehydration operation will vary depending upon the nature ofthe crop and whether the latter has a relatively waxy outer surface. Thesame may be said about the quantities of water introduced onto the cropprior to dehydration. In other words, the amounts required will varydepending upon the nature and relative dryness of the crop. it sufficesto say that the water should be added in quantities sufficient forpreventing the charring or burning of the crop as it passes through theenvironment of heated gases.

The product dehydrated pursuant to the method of this invention has beenfound particularly high in Vitamin E and Vitamin A content. It istheorized that the protection afforded by the water coating preventsdestruction of the beneficial mold on the plants thought to be asource-ofxanthophyll. Also, the high Vitamin A and E content may bearesult of the saving of the highly beneficial and easily destroyedleaves of the crop.

The product protected during dehydration by the application ofa coatingof water has been found to be more palatable because it is free of theobjectionable tastes resulting from the in the dehydration process.These portions are a from burning or charring by the application ofwater thereto as contemplated in this invention.

Having thus described the invention, what I claim as new and desire tobe secured by Letters Patent is:

l. A method of dehydrating a forage crop such as alfalfa or the likeincluding relatively coarse and relatively fine constituents, saidmethod comprising:

applying a controlled amount of water to the outer surface of the cropto wet said outer surface;

promptly thereafter introducing the crop to an environment of heatedgases, said gases being at a temperature sufficiently high for removingmoisture from within the crop constituents;

holding the crop in said environment for a time period sufficient forevaporating said water and substantially drying the crop throughoutwhereby evaporation of the applied water on the outer surface minimizesdestruction of the relatively fine constituents; and

removing the dried crop from said environment.

2. The method as set forth in claim 1, wherein said step of applyingwater to the crop includes the coating of substantially the entire outersurface of the crop with water.

3. The method as set forth in claim 1, wherein is included the step ofadvancing said crop toward said environment, the water being applied tothe crop by spraying on the crop as the latter is advanced.

4. The method as set forth in claim 1, wherein said water is applied tothe crop in amounts of from approximately pounds of water per ton of drymaterial to approximately 1,500 pounds of water per ton ofdry material.

5. The method as set forth in claim 1, wherein said crop is partiallycured alfalfa hay, and wherein said water is applied at a rate ofapproximately 1,500 pounds of water per ton of hay.

6. The method as set forth in claim 1, wherein said crop is introducedinto a rotating drum after the water is applied to the crop, saidenvironment being in the drum, and wherein the temperature of the gasesin said environment at the inlet end ing operation are extremelyvulnerable to burning or charring so protecte thereof is betweenapproximately 2,500 F. to approximately 3,400" F. and the temperature atthe outlet end of said drum is between approximately 200 F. toapproximately 230 F.

7. The method as set forth in claim 3, wherein is included the step ofadding a wetting agent to said water prior to spraying the water on thecrop.

8. The method as set forth in claim 7, wherein said water and wettingagent are sprayed on the crop from above the latter while the crop isadvanced therebeneath.

2. The method as set forth in claim 1, wherein said step of applyingwater to the crop includes the coating of substantially the entire outersurface of the crop with water.
 3. The method as set forth in claim 1,wherein is included the step of advancing said crop toward saidenvironment, the water being applied to the crop by spraying on the cropas the latter is advanced.
 4. The method as set forth in claim 1,wherein said water is applied to the crop in amounts of fromapproximately 100 pounds of water per ton of dry material toapproximately 1,500 pounds of water per ton of dry material.
 5. Themethod as set forth in claim 1, wherein said crop is partially curedalfalfa hay, and wherein said water is applied at a rate ofapproximately 1,500 pounds of water per ton of hay.
 6. The method as setforth in claim 1, wherein said crop is introduced into a rotating drumafter the water is applied to the crop, said environment being in thedrum, and wherein the temperature of the gases in said environment atthe inlet end thereof is between approximately 2,500* F. toapproximately 3, 400* F. and the temperature at the outlet end of saiddrum is between approximately 200* F. to approximately 230* F.
 7. Themethod as set forth in claim 3, wherein is included the step of adding awetting agent to said water prior to spraying the water on the crop. 8.The method as set forth in claim 7, wherein said water and wetting agentare sprayed on the crop from above the latter while the crop is advancedtherebeneath.